SpringCloud Eureka Server

末蓝、 2024-04-19 11:50 63阅读 0赞

本文实战 Eureka Server 集群。

1.  集群工程的配置
2.  docker-compose 编排示例（实际生产环境中，肯定要放在不同的物理机上）

**一、Eureka Server 工程**  
工程代码很简单，工程代码主要包含：  
**1、pom.xml 文件**

<?xml version="1.0" encoding="UTF-8"?>
    <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    	<modelVersion>4.0.0</modelVersion>
    	<parent>
    		<groupId>org.springframework.boot</groupId>
    		<artifactId>spring-boot-starter-parent</artifactId>
    		<version>2.1.8.RELEASE</version>
    		<relativePath/> 
    	</parent>
    	<groupId>com.shanhy</groupId>
    	<artifactId>shanhy-eureka</artifactId>
    	<version>0.0.1-SNAPSHOT</version>
    	<name>shanhy-eureka</name>
    	<description>Eureka project for Spring Boot</description>
    
    	<properties>
    		<java.version>1.8</java.version>
    		<spring-cloud.version>Greenwich.SR3</spring-cloud.version>
    	</properties>
    
    	<dependencies>
    		<dependency>
    			<groupId>org.springframework.cloud</groupId>
    			<artifactId>spring-cloud-starter-netflix-eureka-server</artifactId>
    		</dependency>
    
    		<dependency>
    			<groupId>org.springframework.boot</groupId>
    			<artifactId>spring-boot-starter-test</artifactId>
    			<scope>test</scope>
    		</dependency>
    	</dependencies>
    
    	<dependencyManagement>
    		<dependencies>
    			<dependency>
    				<groupId>org.springframework.cloud</groupId>
    				<artifactId>spring-cloud-dependencies</artifactId>
    				<version>${spring-cloud.version}</version>
    				<type>pom</type>
    				<scope>import</scope>
    			</dependency>
    		</dependencies>
    	</dependencyManagement>
    
    	<build>
    		<finalName>${project.name}</finalName>
    		<plugins>
    			<plugin>
    				<groupId>org.springframework.boot</groupId>
    				<artifactId>spring-boot-maven-plugin</artifactId>
    			</plugin>
    		</plugins>
    	</build>
    
    </project>

**2、启动主Java类**

import org.springframework.boot.SpringApplication;
    import org.springframework.boot.autoconfigure.SpringBootApplication;
    import org.springframework.cloud.netflix.eureka.server.EnableEurekaServer;
    
    @EnableEurekaServer
    @SpringBootApplication
    public class ShanhyEurekaApplication {
    
    	public static void main(String[] args) {
    		SpringApplication.run(ShanhyEurekaApplication.class, args);
    	}
    
    }

**3、配置文件 application.yml**

spring:
      application:
        name: shanhy-eureka
    ---
    spring:
      profiles: eureka-server1
    server:
      port: 8761
    eureka:
      server:
        enable-self-preservation: false  # 开发环境关掉保护机制,快速发现已经挂掉的服务，生产环境需要设置为true提升服务稳定性
      instance:
        hostname: eureka-server1
        prefer-ip-address: true
        instance-id: ${spring.application.name}:${spring.cloud.client.ip-address}:${spring.application.instance_id:${server.port}}
      client:
        serviceUrl:
          defaultZone: http://eureka-server2:8762/eureka/,http://eureka-server3:8763/eureka/
        register-with-eureka: true
    ---
    spring:
      profiles: eureka-server2
    server:
      port: 8762
    eureka:
      server:
        enable-self-preservation: false  # 开发环境关掉保护机制,快速发现已经挂掉的服务，生产环境需要设置为true提升服务稳定性
      instance:
        hostname: eureka-server2
        prefer-ip-address: true
        instance-id: ${spring.application.name}:${spring.cloud.client.ip-address}:${spring.application.instance_id:${server.port}}
      client:
        serviceUrl:
          defaultZone: http://eureka-server1:8761/eureka/,http://eureka-server3:8763/eureka/
        register-with-eureka: true
    ---
    spring:
      profiles: eureka-server3
    server:
      port: 8763
    eureka:
      server:
        enable-self-preservation: false  # 开发环境关掉保护机制,快速发现已经挂掉的服务，生产环境需要设置为true提升服务稳定性
      instance:
        hostname: eureka-server3
        prefer-ip-address: true
        instance-id: ${spring.application.name}:${spring.cloud.client.ip-address}:${spring.application.instance_id:${server.port}}
      client:
        serviceUrl:
          defaultZone: http://eureka-server1:8761/eureka/,http://eureka-server2:8762/eureka/
        register-with-eureka: true

**4、打包和启动**  
先使用 `mvn package` 打包

然后配置本地 host 用于测试

> 127.0.0.1 eureka-server1  
> 127.0.0.1 eureka-server2  
> 127.0.0.1 eureka-server3

最后指定不同 profile 启动3个集群节点

> java -jar shanhy-eureka.jar --spring.profiles.active=eureka-server1  
> java -jar shanhy-eureka.jar --spring.profiles.active=eureka-server2  
> java -jar shanhy-eureka.jar --spring.profiles.active=eureka-server3

在没有全部都启动完成之前，控制台会报错的，意思是还有集群节点服务链接不上。  
完全启动后，浏览器分别访问 http://localhost:8761、http://localhost:8762、http://localhost:8763 可以查看集群状态。

5、docker-compose 编排示例  
前提是你的工程已经使用 dockerfile 构建完成（这个本文不演示）  
假设我们构建的镜像名为 `xzxiaoshan/eureka-server:latest`  
然后创建 docker-compose.yml 内容如下：

version: "3"
    services:
      eureka-server1: 
        image: xzxiaoshan/eureka-server:latest
        container_name: eureka-server1
        hostname: eureka-server1
        networks:
          - eureka-net
        ports:
          - "8761:8761"
        environment:
          - spring.profiles.active=eureka-server1
      eureka-server2:
        image: xzxiaoshan/eureka-server:latest
        hostname: eureka-server2
        container_name: eureka-server2
        networks:
          - eureka-net
        ports:
          - "8762:8762"
        environment:
          - spring.profiles.active=eureka-server2
      eureka-server3:
        image: xzxiaoshan/eureka-server:latest
        hostname: eureka-server3
        container_name: eureka-server3
        networks:
          - eureka-net
        ports:
          - "8763:8763"
        environment:
          - spring.profiles.active=eureka-server3
    networks:
      eureka-net:
        driver: bridge

这个 docker-compose 文件意在示范使用docker 启动eureka服务，实际上这是一个假集群，因为在实际生产中，集群肯定落实在不同的物理机上。不同的物理机之间的docker访问，你可能需要参考一下文章 [《Docker 跨主机网络通讯 flannel+etcd》][Docker _ flannel_etcd] 。

**如果你用了 flannel+etcd 方案，建议所有服务都使用 docker run 来启动，因为docker-compose 会强制给你管理网络，会出现一些问题。**  
3个eureka 服务实例的启动脚本示例：

docker run -itd --name eureka-server1 -p 8761:8761 -e spring.profiles.active=eureka-server1 -e eureka.client.serviceUrl.defaultZone=http://192.168.1.164:8762/eureka/,http://192.168.1.164:8763/eureka/ 192.168.1.163:81/gukesoft/shanhy-eureka:latest
    docker run -itd --name eureka-server2 -p 8762:8762 -e spring.profiles.active=eureka-server2 -e eureka.client.serviceUrl.defaultZone=http://192.168.1.164:8761/eureka/,http://192.168.1.164:8763/eureka/ 192.168.1.163:81/gukesoft/shanhy-eureka:latest
    docker run -itd --name eureka-server3 -p 8763:8763 -e spring.profiles.active=eureka-server3 -e eureka.client.serviceUrl.defaultZone=http://192.168.1.164:8761/eureka/,http://192.168.1.164:8762/eureka/ 192.168.1.163:81/gukesoft/shanhy-eureka:latest

PS：如果你上了K8S和ServiceMesh，Eureka 可能你就不需要了。

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[Docker _ flannel_etcd]: https://blog.csdn.net/catoop/article/details/100178305